The present invention relates to syringes, and more particularly to a safety syringe which enables the needle to be received inside the barrel after the use of the syringe.
A safety syringe allows the user (the nurse or surgeon) to pull the needle backwards to the inside of the barrel after the use of the syringe. If the needle of a syringe is kept on the outside of the barrel after its use, the needle of the syringe may injure the person who handles waste medical instruments accidentally. Such safety syringes are disclosed in Taiwan Pat. No. 253192 and No. 332433. However, these safety syringes are still not satisfactory in function. During injection, when the plunger is pushed forwards into engagement with the needle, vibration will be caused and a patient will feel pain. In addition, the needle can not be disassembled. Therefore, it is necessary to have a improved design for a safety syringe which can reduce the vibration during the engagement of a needle and a plunger.